In the field of regenerative medical research aimed at the replacement of organs and tissues, there is a need for the development of a technology for constructing artificial three-dimensional cellular tissue. A microfiber is known to be able to serve as the basic units for forming such three-dimensional cellular tissue, and the microfiber has a core-shell structure in which a fiber core (core portion), obtained by mixing cells into an extracellular matrix component in the form of collagen or fibrin, is covered with an outer shell portion such as an alginate gel (Patent Document 1). The microfiber has sufficient mechanical strength for handling, and enables the construction of three-dimensional cellular tissue while maintaining cell function. In addition, the microfiber can be prepared using various types of cells, including nerve cells, muscle cells, fibroblasts and epithelial cells.
The development of technology for artificially constructing internal tissues having a luminal structure such as blood vessels and lymph ducts is also sought in the field of regenerative medical research. A conventionally known method for producing blood vessel-like structures from cells comprises preparing long, narrow openings in a mass of collagen gel by molding and then culturing cells such as vascular endothelial cells in the inner wall thereof.
It is known that when vascular endothelial cells are introduced into the core portion of the aforementioned microfiber and cultured with an extracellular matrix component, the vascular endothelial cells spontaneously forms lumen within the microfibers (Non-Patent Document 1).